Budget airline Jetstar will cut 10 per cent of its domestic flights in January and consider selling some planes as it battles with two unions over pay and conditions.

Ground crew represented by the Transport Workers Union and the Australian Federation of Air Pilots started industrial action on Friday and continued over the weekend.

Jetstar cut more than 100 flights between Friday and Sunday as a result of the double-pronged action. It faces more protected industrial action from baggage handlers and ramp workers again on Thursday, with pilots pledging low-level work bans until December 20.

On Monday, the airline said reducing its January flight schedules would reduce disruption to passengers, who will be able to reschedule flights or get refunds.

Flights hit will mostly be high-frequency routes to enable as much passenger flexibility as possible.

Jetstar said the ongoing industrial action will cost it $20 million-$25 million.

The budget airline has rejected workers’ demands for pay increases, minimum hours on the job and safety improvements.

Jetstar said it had offered a 3 per cent pay rise, but the TWU also wants more rest breaks, a guaranteed 12-hour break between shifts, guaranteed 30 hours a week and annual wage increases of 4 per cent.

The AFAP is pursuing a 3 per cent annual increase and has attacked Jetstar’s claims that pilots want an effective 15 per cent jump. In a Facebook post on Sunday, the union said Jetstar pilots did “certain shifts that no other pilots in Australia will do, in particular back-of-the-clock shifts – very long, very fatiguing shifts”.

“The AFAP and Jetstar pilots are frustrated by Jetstar continually inventing figures to suit themselves,” AFAP executive director Simon Lutton said.

“It is highly convenient for Jetstar management to claim that two four-hour work stoppages over the weekend will result in flight cancellations in January when no pilot action is planned past this Friday.”

The pilots union said it remained committed to reaching an agreement and urged Jetstar to return to the bargaining table after the Christmas holidays.

TWU national secretary Michael Kaine said Jetstar could have used the money spent on “cancelling flights and upsetting holiday plans” to resolve its dispute with workers.

But the airline called the unions’ claims “unsustainable”.

“In the case of the pilots, the union is asking for what amounts to a 15 per cent wage increase in the first year, in a group where captains earn more than $300,000 a year,” chief executive Gareth Evans said.

“For some groups, their salaries would increase by $60,000. We can’t agree to that.”

He said the TWU’s claims equate to a 12 per cent increase in costs for Jetstar ground crew, who earn about $70,000 a year part time (or about $90,000 full time).

“There’s no doubt that industrial action is expensive and frustrating, but we have to hold the line on costs or it threatens the long term sustainability of our business,” Mr Evans said.

Amid the pay stoush, Jetstar said it was also reviewing the viability of longer-haul international flights by its 787-8 fleet, including trips to Honolulu. The airline said three of the fleet were flying on “loss-making and marginal international routes”.

A final decision on the future of those flights is expected in March 2020.

-with AAP